The present invention relates to a method and an apparatus for fusing a heat curable toner to a carrier sheet.
For printing different toners are known for forming an image or influencing the gloss of an image. One type of toner is a heat curable (cross-linkable) toner, which is typically fused to a carrier sheet by moving the carrier sheet and toner through a nip formed between two pressure rollers. Typically, one of the pressure rollers is heated above a glass transformation temperature of the toner, to melt the toner thereby intimately fusing the same to the carrier sheet. After passing the carrier sheet and toner through the nip between the pressure rollers, the toner is typically quickly cooled to a temperature below its glass transformation temperature.
During this fusing step, the thermally curable toner is only partially cured due to the short time it remains above the glass transformation temperature. Such a thermally curable toner, however, may be problematic in certain applications, in which a high thermal stability is required. Such an application is for example a printed car manual, which may be heated within a car to high temperatures above the glass transformation temperature of the toner. If this occurs, the pages of the car manuals could be fused together. Similar problems may arise, when printed media are X-rayed for sterilization to avoid anthrax attacks in US Government offices.